PLUTONIUM AND TRACER PARTICLE RESUSPENSION:
AN OVERVIEW OF SELECTED BATTELLE-NORTHWEST EXPERIMENTS
G. A. Sehmel
Battelle, Pacific Northwest Laboratories, Richland, Washington
ABSTRACT
Plutonium resuspension at Rocky Flats was determined in July 1973, by
measuring airborne plutonium as a function of sampling height and of wind
speed. The maximum airborne plutonium-239 concentration was 3700 aCi/m>.
The maximum plutonium-239 activity per gram of collected airborne soil was
50 pCi/g. Airborne plutonium concentrations were shown to increase as the
sixth power of wind speed, but the data were very imprecise.
In_measurement of fallout resuspension caused by burning vegetation, the
37Cs concentration in a forest fire smoke plume was 22 times the concen-
tration in ambient air.
Resuspension rates for a_man walking across a tracer area on an asphalt sur-
face ranged from 1 x 1075 to 7 x 10-4 fraction of tracer resuspended/pass.
For vehicular traffic driven on a tracer lane, resuspension rates from the
asphalt surface ranged from 10-4 to 10-2 fraction resuspended/pass.
When
the vehicle was driven on the lane adjacent to the tracer lane, resuspension
rates were smaller, ranging from 10-5 to 10-3 fraction resuspended/pass.
Resuspension rates decreased when the tracer had been on the ground for
several days. In comparison to the asphalt surface, vehicle-caused tracer
resuspension rates from a cheat grass area were lower, ranging from 10-° to
10-4 fraction resuspended/pass.
Wind caused tracer resuspension rates were on the order of 10711 fraction
resuspended/sec for nonrespirable particles. Resuspension rates for respirable particles increased as the 4.8th power of wind speed, ranging from
10-11 to 10-7 fraction resuspended/sec.
In another study, airborne respi-
rable soil concentrations measured as a function of wind speed increased
as the 0.6 to 3.2 power of wind speed.
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